1995A&A...297L..41V

The 24 binary radio pulsars with nearly circular orbits and low-mass companions (0.2-0.4xM_☉ helium white dwarfs in most cases) show a remarkable correlation between spin period P and orbital period P_or and between dipole surface magnetic field strength B_S, and P_or. The observed B_S, vs. P_or relation is consistent with increasing decay of the neutron-star magnetic field with increasing amounts of matter accreted, as has been proposed on theoretical grounds by various authors. Neutron stars in binaries to which more than 0.45xfxM_☉ was transferred have field strengths below 10⁹G, where f(=<1) is the fraction of the transferred matter that is not lost from the systems. The only one exception in the galactic disk (out of twelve systems) is the PSR 1831-00 system, in which >0.7xfxM_☉ was transferred but the pulsar still has a strong magnetic field (∼0.8x10¹¹G). Adopting the field decay by accretion models, the only way in which this can be explained is that the neutron star in this system was formed near the end of the mass-transfer phase, by the accretion-induced collapse (AIC) of a white dwarf.